Fix `make check` running doctests
Support regex group substitutions in more fields

You can now use $0, $1, $n to refer to the nth regex match in config.cfg
for bus name, object path, interface name and method name.
run-loop.sh: Reload the daemon when the config changes as well
Fix method calls taking no arguments
Terminate responses with a newline

This makes it easier to use curl to test it at the command line.